The proposed research involves purification of placental cytochrome P-450 and other components of the aromatase enzyme system and a search for different species of aromatase enzyme for the 16 hydroxylated and non-hydroxylated androgens. Knowledge about the placental system will then be applied to ovarian tissue. From appropriate rat, hamster, and rabbit animal models, ovarian granulosa and theca cells will be isolated at various ages and stages of follicular development. The temporal appearance and regulation of gonadotropic membrane receptors, intracellular cyclic nucleotides and estrogen production will be studied and correlated.